[Disordered alpha 2-adrenoreceptor function in hemodialysis patients with renal anemia--a possible cause of increased blood pressure in relation to recombinant human erythropoietin?].

Nine patients on maintenance hemodialysis and transfusion-demanding renal anemia (group A) were treated with rHuEPO 120 IU/kg i.v. three times per week. Hemoglobin-content was raised from 7.2 +/- 0.9 to 10.4 +/- 0.8 g/dl. In all patients blood pressure rose, three patients developed arterial hypertension. Mean diastoloic blood pressure was 66 +/- 12 and 78 +/- 16 mmHg (p less than 0.001) before and after rHuEPO. Rise in blood pressure was accompanied by a significant fall in plasma-noradrenaline-levels (from 498 +/- 100 to 383 +/- 75 pg/ml; p less than 0.05) and alpha 2-adrenoceptor-density (from 574 +/- 76 to 384 +/- 49; p less than 0.05). Compared to nine patients on maintenance hemodialysis and hematocrit over 30% (group B), patients with severe renal anemia (group A before treatment) had higher densities of alpha 2-adrenoceptors (574 +/- 76 vs. 218 +/- 32; p less than 0.001) despite higher plasma-noradrenaline-levels (498 +/- 100 vs. 399 +/- 63; n.s.). We suppose a anemia-related disturbance of alpha 2-receptor-function with the result of abolished receptor down-regulation and impaired vascular reagibility to vasoconstricting stimuli. With the correction of anemia receptor-function improves, receptor down-regulation as well as vascular reagibility is re-established resulting in augmented vascular resistance and higher blood pressure.